1. Field of the Invention
The present invention relates to a sheet feeder for a printer, and specifically to a sheet feeder for a printer which selectively drives one of plural sheet feeding mechanisms to feed the corresponding sheet to a printing section of the printer.
2. Description of the Related Art
Conventional sheet feeders for printers include, for example, those capable of permitting plural sheet feeding modes such as an ACSF mode in which an auto cut sheet feeder (ACSF) is driven to automatically feed cut sheets one after another to a printing section, a continuous sheet feeding mode in which a tractor is driven to continuously feed a continuous sheet to a printing section, and a manual feeding mode in which sheet feed rollers arranged at a sheet-input slot of a printer are driven to manually feed a cut sheet to a printing section. In a printer equipped with such sheet feeding modes, respective drive mechanisms for ACSF, tractor, sheet feed rollers and the like for the various sheet feeding modes are associated with their corresponding sheet feeding mode selection keys on a control panel. A desired sheet feeding mode is selected upon feeding paper sheets, whereby the drive mechanism corresponding to the sheet feeding mode so selected is actuated. As a result, a paper sheet associated with the drive mechanism is automatically fed to a printing section.
Sheet feeders for printers, in which the feeding of a sheet is automated as described above, include those capable of storing the sheet feeding mode before removal of the power supply in a non-volatile manner by using an EEPROM or the like. Even when the power supply is once turned off to perform maintenance work for the elimination of a trouble such as a paper jam, such a sheet feeder is automatically reset in the sheet feeding mode before the removal of the power supply as soon as the power supply is turned on again.
However, such a sheet feeder is accompanied by the irksomeness that after its power supply has been turned off and any jammed sheet has been removed, a sheet different from that being printed before the removal of the power supply must be manually set in the printing section before the power supply is turned on again. Basically, no manual sheet setting is required for an automated sheet feeder. Such manual sheet setting is however needed in some instances, for example, upon jamming of a paper sheet or loading a continuous sheet on the feeder. Whenever a sheet is set by such a manual operation, a conventional sheet feeder automatically ejects the manually-set sheet and feeds a sheet, which corresponds to the paper feeding mode before the removal of the power supply, to the printing section. As a result, the operator cannot print on the intended sheet. If the sheet set by this manual operation is a continuous sheet, printing on the intended continuous sheet is not feasible and moreover, the continuous sheet may be ejected over a substantial length. Such large wasting of a continuous sheet takes place when the sheet feeder is reactuated in the cut sheet feeding mode.